It would be interesting, to say the least, if Texas invoked their right to sucede. Big news for the media. Everyone would be watchin the news, although everyone here does not trust the news. Anyway, even if Texas could work out the logistics of such a move (Texas citizens for and against, doing without federal assistance, removal of all federal employees, installation and maintenance of an army, dealing with the thousands of civil suits, maintaining their highways, having some other agency delivering their mail, establishing border security on all sides without Border Patrol to the south, etc.), even if Obama didn't exist, the U.S. gov't would never allow it. The first national guard person who got killed (and you know the national guard would be called in), the entire weight and power of the federal gov't would fall on Texas like a hammer. A civil war will never happen again in the U.S. This ain't the 1800's.
Remember when the Democrats got mad when Bush was elected to his last term? They threatened to move to Canada, only to find out Canadian citizenship is not so easily acquired. They sucked it up and stayed put. So will Texas.